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That’s a good question to ponder overnight. From science writer George Musser:
Let’s Rethink Space
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And in the past 20 years, I’ve witnessed a remarkable evolution in attitudes among physicists toward locality. In my career as a science writer and editor, I have had the privilege of talking to scientists from a wide range of communities—people who study everything from subatomic particles to black holes to the grand structure of the cosmos. Over and over, I heard some variant of: “Well, it’s weird, and I wouldn’t have believed it if I hadn’t seen if for myself, but it looks like the world has just got to be nonlocal.”
To make sense of nonlocality, the first step is to invert our usual understanding of space. Physicists and philosophers can define space as the fact that the natural world has a very specific structure to it. Instead of saying that space brings order to the world, you can say that the world is ordered and space is a convenient notion for describing that order. We perceive that things affect one another in a certain way and, from that, we assign them locations in space. This structure has two important aspects. First, the influences that act on us are hierarchical. Some things affect us more than other things do, and from this variation we infer their distance. A weak effect means far apart; a strong effect implies proximity. The philosopher David Albert calls this definition of distance “interactive distance.” “What it means that the lion is close to me is that it might hurt me,” he says. This is the opposite of our usual mode of thinking. Rather than cry, “Watch out, the lion is close, it might pounce!” we exclaim, “Uh-oh, the lion might pounce on me; I guess it must be close.”
The second aspect of the spatial structure is that diverse influences are mutually consistent. If a rhinoceros is also able to hurt me, it must be close, too. And if both a lion and a rhino are able to hurt me, then the lion and rhino should also be able to hurt each other. (Indeed, my survival depends on it.) From this patterning of influences, we extract space. If the threat posed by predators couldn’t be expressed in terms of spatial distance, space would cease to be meaningful. A less morbid example is triangulation. The signal bars on your mobile phone indicate the strength of the phone’s connection to a cell tower and therefore your distance from that tower. In an emergency, the phone company can locate your phone by measuring your signal at several towers and using triangulation or the related technique of trilateration. The fact that the measurements converge on a single location is what it means for you to have a location.
The nice thing about defining space in terms of structure is that it sidesteps some of the long-running disputes over the nature of space. More.
See also: Arrow of time points to missing dark matter?
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